Device for driving the platen of a press

ABSTRACT

A device for driving the platen of a press, a piston mounted to slide in a cylinder unit, said piston being hydraulically driven, and another piston mounted to slide in a bore of the first piston, said second piston being securely fixed to said platen, and said first piston having means for locking said second piston in its bore, so that said platen can be subjected to a rapid positioning movement by the displacement of said second piston and to a slower movement by the displacement of said first piston when the latter is subjected to high pressure, the movement of said first piston being transmitted to said platen by said locking means.

United States Patent l72| Inventor Robert Ange Marie Nouel Paris, France [21 Appl. No. 838,101 [22] Filed July 1, I969 [45] Patented Sept. 7, I971 [73] Assignee Inventions Finance Corporation Washington, D.C.

[54] DEVICE FOR DRIVING THE PLATEN OF A PRESS 11 Claims, 7 Drawing Figs.

[52] US. Cl 100/218, 18/30 LV, 100/257, 100/269 [51] Int. Cl 83Gb 15/32 [50] Field of Search 100/257, 269, 218; 72/453; 18/30 LA, 30 LV, 29, 52; 92/61, 62, 24

[56] References Cited UNITED STATES PATENTS 512,790 1/1894 Bachman 92/29 X 2,689,978 H 9/1954 Roger IS/3 0 AHomer-Theodore bishoff 4/1961 Swick et al 100/257 3,103,876 9/1963 Ferranti.. 100/269 X 3,270,372 9/1966 Hesse 18/30 FOREIGN PATENTS 998,665 7/1965 Great Britain 18/30 1,014,093 12/1965 Great Britain 18/30 Primary Examiner-Billy J. Wilhite to said platen by said locking means.

ABSTRACT: A device for driving the platen of a press, a

PATENTEBSEP 7:921 I sum 2 OF 6 INVENTOR ROBERT ANGE MARIE NOUEL ATTORNEY PATENTEU SEP "H971 3,603,248

SHEET 3 QF 6 INVENTOR ROBERT ANGE MARIE NOUEL A TTORNE PATENTED SEP 1 IBYI 3.603; 248

' sum u I]? 6 INVENTOI? ROBERT ANGE MARIE NOUEL ATTORNEY PATENTEDSEP mm 3.603248 SHEET 6 BF 6 lNl/E/VT'OI? ROBERT ANGE MARIE NOUEL.

ATTORNEY DEVICE FORDRIVING THE PLATEN OF A PRESS The present invention relates to a drive for the platen of a press.

The presses to which the present invention relates are of the type which are composed mainly of a platen and a drive for that platen. The drive comprises a cylinder unit in which a piston slides. The piston, which is generally moved hydraulically, displaces the platen and forces the latter against a fixed member. The platen and the fixed member may take different forms according to whether the press is intended for drawing, stamping or forming metals or plastic materials by compression, injection, transfer or injection-compression, etc.

In known presses of this type, the considerable weight and bulk of the piston, resulting from the-high pressures to be used, limit the speed of movementof the piston. The result is that the length of the stroke of the piston must be made as short as possible so as not to increase idle times unduly. In addition, the displacement of a heavy piston requires a highpowered drive.

The present invention provides a device for driving the press platen which enables the latter to make longstrokes at high speeds and with a minimum consumption of energy.

In the case of a forming press, the device according .to the invention also enables the internal stresses of the formed.

materials to be considerably reduced. Another advantage of the invention consists in that ejection of the formed materials may be effected very simply.

According to the present invention, there is provided in a device for driving the platen of a press, a piston mounted to slideina cylinder unit, said piston being hydraulically driven, and another piston mounted to slide in a bore of the first piston, said second piston being securely fixed to said platen, and said first piston having means for locking said second piston in its bore, so that said platen can be subjected to a rapid positioning movement by the displacement of said second piston and to a slower movement by the displacement of said first piston when the latter is subjected to high pres sure, the movement of said first piston being transmitted to said platen by said locking means.

Other advantages and characteristics of the present invention will appear in the following description of preferred embodiments of the platen drive, given by way of example with the aid of the accompanying drawings, in which:

FIG. 1 is an axial section through a press provided with the platen drive according to the invention, the platen being in the raised position. v

FIG. 2 is a view similar to that of FIG. 1, the platen being in the lowered position.

FIG. 3 is asection along the line III-Ill of FIG. 1.

FIG. 4 is a section along the line lV-IV of FIG. 2.

FIG. 5 shows schematically the means for hydraulically driving the press.

FIG. 6 shows a part-axial section through another embodiment of the press, and

FIG. 7 shows another embodiment of the press of FIG. 1.

In the FIGURES, the platen drive has been shown as applied to a column-type press. This press has four vertical columns I, 2, 3, 4 connected at ground level by baseplate 5, fixed to the columns by nuts 6; The columns are connected at the top by a unit 7, fixed by nuts 8. A platen 9 is mounted to slide on these columns so as to be able to move between the baseplate 5 and the unit 7; The baseplate 5 and the platen 9 have on their opposite faces members 10, 11 which are intended to be forced ing movement of the piston, and the hydraulic pressure for the against each other. The members 10, 11 may be constituted in together define a chamber 15 into which a conduit 16 leads.

The ring 14 may serveas an ultimate stop during the descendreturn, or upward, movement of the piston 13 is applied to that ring through conduit 16 and chamber 15. The part'13a of large diameter of the piston slides in a part 12b of the bore 12. A conduit 17 leads into chamber 18 whose diameter is larger than that of the chamber 15. Given the largesurface of application for the pressure fluid fed to chamber 18 through conduit 17, it is possible to apply a considerable force to the piston 13, in order to cause it to descend.

According to the present invention, a bore 78 is provided in the piston 13, the bore serving as a cylinder for a piston 19. The piston 19 is securely fixed to theplaten9 by an assembly composed of screw 20 and nut 21; The nut 21 may rotate in a ring 22. The latter may be locked against rotation by screws 23. Manipulating holes 24 are formed in the nut 21. Rotation of the nut 21 enables the length of the stroke of the platen 9 to be adjusted in a very simple manner.

The piston 19 is hydraulically controlled by differential pressure, the pressure fluid being fed through two conduits 25,

26. It will be seen that the pressure fluid passing throughthe conduit 25 acts on a larger surface than the fluid passing through conduit 26, so that the piston 19is pushed downwards when pressure fluid passes through the two conduits 25 and 26. According to the invention, the piston 13 has meansufor locking the piston 19 in its bore. These locking means are constituted by two claws 27, 28 slidably mounted inchambers 29, 30. The claws are moved by hydraulic jacks 31,32 so'that they can be placed in the path of displacement of the piston 19 (FIGS. 2 and 4). Claw 27 has a rod 33, and claw 28 a rod 34.

These rods cooperate with electric switches 35, 36.=and 37, 38,

in order to synchronize the action of the jacks 31, 32.

The piston 19 cooperates with a tube 39 'fixed to aplate 40 I by claws 41 and screws 42. The plate 40-is fixed to the unit-7 by screws 43. 7

Another tube 44, mounted in a threaded bore of the screw 20, ensures the seal of the chamber 45 into which-the conduit 25 opens.

Anejection rod 46 is fixed to the plate 40 by-means ofan't adjusting device composed of a cone 47 and a conical gripper 48. The piston 19 and the two tubes 39, 44 are hollow so as to provide a passage for the ejection rod 46, tightening of the gripper being ensured by screws 49. The ejection rod passes through a central bore 50oF the platen 9;

In order to explain the operation, FIG. 5 shows by way of example a hydraulic actuating assembly of the drive'for the platen 9; This assembly comprises a motor 51 driving. a hydraulic pump 52 by means of a clutch .53. The pump52 draws fluid for the transmission of power from a tankv 54 through a filter 55. Pressure fluid leaving the pump 52 is fed through the conduits 56, 57, 58 towards electrovalvcs 59,- 60, 61. The fluid may be returned directly to the tank 54 through a safety valve 62 which protects the installation. The elec trovalvc 59 controls the displacement of piston 19, ,electrovalve 60 controls the jacks 31, 32, and the electrovalve 61 the displacement of the piston 13.

On the downstream end of the electrovalve 61, three devices are provided for optional use and are constituted by a nonreturn valve 62, a sequence valve 63 and an intensifier 64.

The operation of the drive is as follows: (in the following, opening" designates the upward displacement of the platen 9, and closing" its downward displacement).

CLOSING At the start, the press is in the position shown in FIG. 1.

Actuation of button 65 of the electrovalve 59 permits the simultaneous supply of both conduits 25 and 26 withpressure fluid. Because of the difference in'the cross sections of chambers 66 and 45, the piston 19 descends and the parts 10and 11 draw near to each other and close. As soon as the parts 10 and 11 make contact, a stroke-limit switch (not shown) energizes the electrovalve 60. The oil enters the chambers 67 ofthe jacks 21, 32 through the conduits 68 and leaves chambers 69 of the jacks 31, 32 through conduits 70. The two claws 27, 28 move towards the axis of the drive. At the end of the stroke (FIG. 4), the contacts 36, 38 energize the electrovalve 61. The pressure liquid is then charged into the chamber 18 through the conduit 17 while the chamber is relieved by the conduit 16. The main piston 13 then tends to move downwards carry ing along the platen as well as the piston 19 by means of the claws 27, 28 which abut against ring 72. As pressure continues to build up in the chamber 18, actuator 73 of the valve 63 begins to act and pressure liquid is directed to the intensifier 64. The pressure in the chamber 18 is then multiplied progressively according to the ratio of the intensifier. The nonreturn device 62 is closed while the pressure in the chamber is at its maximum.

lt will be seen that high pressure is applied only during a short stroke of the platen 9. The complete stroke can be long the main piston. Therefore, internal stresses are not created in the moulded article.

OPENING The electrovalve 61 is deenergized. Pressure liquid then enters the chamber 15 through the conduit 16 while the pressure liquid in the chamber 18 is discharged to the tank 54 through the nonreturn device 62 which was opened previously by its actuator 73 (shown in dotted lines).

The main piston 13 rises again, opening the mould.

When the piston 13 has finished its stroke, it actuates a contact (not shown) which dccncrgizcs the valve 60 so that the pressure liquid penetrates into the conduit 70 while the conduit 68 is connected to the tank 54. The pistons of the jacks 31, 32 move back so that the claws 27, 28 disappear in order to clear the way for the piston 19.

The claws 27, 28 actuate the contacts 35, 37 at the .end of the stroke. The contacts act on the electrovalve 59 so that the pressure liquid enters chamber 66 through the conduit 26. The liquid in the chamber 45 returns to the tank through conduit 25. The assembly composed of piston 19 and platen 9 rises rapidly again. At the end of its stroke, this assembly actuates a contact which acts on the electrovalve 59 so that the conduits 25 and 26 are closed and the assembly is locked.

During the upward stroke of the piston 19, the fixed ejection rod 46 expels the moulded member from the upper mould 10 of the mould-carrying platen 9. The gripper 48 tends to im crease its held during the ejection.

FIG. 6 shows another embodiment of the device for the platen 9.

The drive is arranged according to the same principle as in the preceding Figures, a piston 19' being mounted to slide in a main piston 13', and this latter comprises means for locking the piston 13. The difference with respect to the first embodiment resides mainly in the hydraulic drive of the pistons 13 and 19'.

In the case of FIG. 6, the piston 19' is driven by two doubleacting jacks (only one, 76, being shown) connected to conduits 25, 26 and passing through upper plate 40', in the unit 7. Each jack comprises a piston 77, connected to the piston 19 by a tie rod 78, anda crosshead 79. One of the advantagesv of this assembly stems from the fact that the cylinder is fixed, permitting the pressure oil to pass through rigid pipes. Another advantage resides in the fact that the walls of the piston 13' may be thicker because of the reduction of the outcase of the first embodiment, but its upward stroke is effected by two auxiliary shifting devices 80, (one being shown) arranged in the unit ,7. This arrangement also enablesthe ring 14 of the piston 13 and the crosshead 40 to be eliminated, thereby making access to the sealingjoints easier.

In the still further embodiment of FIG. 7, the locking means are constituted by a single horseshoe-shaped claw 28' actuated by a single jack 31.

The conduits connecting the input line 25' to the chamber 66 and the input line 26' to the chamber 45, respectively, are

preferably formed in the body of tube 44. Thus, two advantages are obtained: on the one hand, the chambers 66 and 45 have identical cross sections, which enables the piston 19 to be actuated by means of a closed hydraulic circuit (comprising, for example, a volumetric pump), and on the other hand, the input lines 25 and 26' are fixed during the opera tion, thereby facilitating their connection.

What is claimed is:

1. A device for driving the platen of a press, comprising a frame, a fixed platen and a movable platen mounted on said frame, a cylinder secured to said frame, a piston having a smooth, uninterrupted bore and mounted to slide in said cylinder, a second piston having a smooth uninterrupted outer surface slidably engaged in said bore of the first piston, said second piston being connected at one end thereof to said movable platen so as to move the latter axially of the cylinder and the connection being such as to prevent relative rotation of the second piston and the movable platen, and means for locking said second piston in the bore of the first piston, so that said platen can be subjected to a rapid positioning movement by the displacement of said second piston and to a slower movement by the displacement of said first piston when the latter is subjected to high pressure, the movement of said first piston being transmitted to said platen by said locking means, said locking means including a cavity in the wall of said first piston opening into the bore of the first piston, a claw mounted to slide in said cavity from a retracted position wholly therein to a locking position partly extended into the bore of the first piston'and behind the other end of said second piston so as to prevent displacement of the second piston axially of the first piston, and pressure fluid means for selectively moving said claw to its retracted and locking positions.

2. A device according to claim 1, in which the first piston forms the piston of a pressure fluid double-acting shifting device.

3. A device according to claim 1, in which the second piston formsthe piston of a pressure fluid shifting device with differential pressure.

4. A device according to claim 1, in which the second piston forms the piston of a pressure fluid shifting device for displacement in one direction and is subjected to the action of at least one separate pressure fluid shifting device for displacement in the opposite direction, the latter shifting device being mounted in the cylinder of the first piston.

S. A device according to claim 1, in which the second piston is securely connected to at least one double-acting pressure fluid shifting device which is mounted in the cylinder of the first piston.

6. A device according to claim 1, which further comprises an ejection rod which is coaxial to the two pistons, the latter being hollow in order to form a passage for said rod.

7. A device according to claim 1, in which the second piston is connected to said platen by a screwnut assembly which enables the distance between the platen and the second piston to be adjusted. i v

8. A device according to claim 1, in which the platen of the press is guided by four columns, the cylinder unit of the first piston being mounted in the upper part of these columns, so that the two pistons are vertical and the platen is subjected to a vertical displacement.

9. A device according to claim 1, in which the locking means are constituted by a single horseshoe-shaped claw, actuated by a jaek I07 A device according to claim 1, in which the second 11. Adevice according to claim 1, in which the first piston is iston is internally guided in a fixed tube, the conduits of the made in two parts, said locking means comprising two cavities ressure fluid circuit actuating the second piston being formed and two locking claws housed in said cavities in the connecin the fixcd tube. tion zone of these parts. 

1. A device for driving the platen of a press, comprising a frame, a fixed platen and a movable platen mounted on said frame, a cylinder secured to said frame, a piston having a smooth, uninterrupted bore and mounted to slide in said cylinder, a second piston having a smooth uninterrupted outer surface slidably engaged in said bore of the first piston, said second piston being connected at one end thereof to said movable platen so as to move the latter axially of the cylinder and the connection being such as to prevent relative rotation of the second piston and the movable platen, and means for locking said second piston in the bore of the first piston, so that said platen can be subjected to a rapid positioning movement by the displacement of said second piston and to a slower movement by the displacement of said first piston when the latter is subjected to high pressure, the movement of said first piston being transmitted to said platen by said locking means, said locking means including a cavity in the wall of said first piston opening into the bore of the first piston, a claw mounted to slide in said cavity from a retracted position wholly therein to a locking position partly extended into the bore of the first piston and behind the other end of said second piston so as to prevent displacement of the second piston axially of the first piston, and pressure fluid means for selectively moving said claw to its retracted and locking positions.
 2. A device according to claim 1, in which the first piston forms the piston of a pressure fluid double-acting shifting device.
 3. A device according to claim 1, in which the secOnd piston forms the piston of a pressure fluid shifting device with differential pressure.
 4. A device according to claim 1, in which the second piston forms the piston of a pressure fluid shifting device for displacement in one direction and is subjected to the action of at least one separate pressure fluid shifting device for displacement in the opposite direction, the latter shifting device being mounted in the cylinder of the first piston.
 5. A device according to claim 1, in which the second piston is securely connected to at least one double-acting pressure fluid shifting device which is mounted in the cylinder of the first piston.
 6. A device according to claim 1, which further comprises an ejection rod which is coaxial to the two pistons, the latter being hollow in order to form a passage for said rod.
 7. A device according to claim 1, in which the second piston is connected to said platen by a screwnut assembly which enables the distance between the platen and the second piston to be adjusted.
 8. A device according to claim 1, in which the platen of the press is guided by four columns, the cylinder unit of the first piston being mounted in the upper part of these columns, so that the two pistons are vertical and the platen is subjected to a vertical displacement.
 9. A device according to claim 1, in which the locking means are constituted by a single horseshoe-shaped claw, actuated by a jack.
 10. A device according to claim 1, in which the second piston is internally guided in a fixed tube, the conduits of the pressure fluid circuit actuating the second piston being formed in the fixed tube.
 11. A device according to claim 1, in which the first piston is made in two parts, said locking means comprising two cavities and two locking claws housed in said cavities in the connection zone of these parts. 